The invention relates to apparatus for moving objects, such as grippers of inserters for workpieces, between predetermined positions. More particularly, the invention relates to improvements in apparatus for moving grippers or other objects between two spaced apart positions along a composite path in a plurality of mutually inclined directions.
Grippers which can be moved in the apparatus of the present invention can be used to accept individually supplied workpieces and to move the thus supplied workpieces to a predetermined delivery position for acceptance by a work holder or the like, e.g., in a machine tool.
Apparatus for moving grippers of inserters for workpieces or the like are disclosed, for example, in German Auslegeschrift No. 27 42 103. This publication discloses an apparatus wherein a carriage is movable up and down along vertical guide rails. The carriage supports a first end portion of a supporting rod which is movable longitudinally in a horizontal direction and the free second end portion of which carries a gripper holding device. The rod is movable forwardly and backwards by a lever one end of which is coupled to the rod and the other end of which is connected to the housing of the apparatus. A median portion of the lever carries a roller which tracks a cam of a rotary drum-shaped cam holder.
A drawback of the just discussed conventional apparatus is that it cannot move the gripper between its end positions with a requisite degree of accuracy and reproducibility. This is believed to be attributable to the utilization of link trains wherein errors due to manufacturing tolerances and/or wear are multiplied to thus cause pronounced departures of actual positions of the gripper from its desired or optimum positions. Moreover, various movements must take place in a very rapid sequence.